Topic 7- Homeostasis Flashcards
What is the hormonal system?
The Collections of glands in the body that release hormones.
What is homeostasis?
The constant maintenance of internal conditions to maintain optimal conditions for cellular reactions. E.g core temperature, pH.
What are hormones?
They are chemical messengers, they take more time to get around the body than electrical messengers. They are transported by the blood and carried to their target organs.
Define metabolic rate?
The rate at which the energy stirred in your food is transferred by all the reactions that take place in your body to keep you alive.
Why do chemical messengers, such as hormones take more time to travel around the body and work than electrical messengers, such as neurones?
Hormones travel in the blood which therefore takes longer. Neurones travel using impulses.
Give some examples of endocrine glands:
- Pituitary gland
- adrenals
- ovaries
- tested
- pancreas.
What is an endocrine gland?
An organ that makes and released hormones into the blood.
Where is the pituitary gland located and what hormones does it create and release?
Located in brain underneath lymphocytes. Releases many hormones:
- FSH (Follicle Stimulating Hormone)
- LH (Luteinising Hormone)
- ACTH
- Growth hormones
Where is the thyroid gland located, what does it do and what hormones does it release?
It releases the hormone thyroxine and is responsible for controlling metabolism. It is located just below the throat.
What hormones do ovaries release?
They release the sex hormone oestrogen and progesterone. It is responsible for growth characteristics (puberty).
Where is the adrenalin gland located and what hormone does it release?
Located in top of the kidneys. Releases the hormone adrenalin. Responsible for the ‘flight or fight’ mechanism associated with danger.
What hormone does the tested release?
Releases the sex hormone testosterone. Responsible fo growth characteristics in makes e.g puberty.
What hormone does the pancreas release and where is it located?
Located behind the stomach. Contains cells that release insulin and glucagon. Helps keep blood sugar levels safe.
What is meant by target organ?
An organ affected by a specific hormone.
How will a hormone affect its target organ?
It will affect the organ by changing what the organ is doing. E.g growth hormones stimulate cells in muscles and bones to divide.l it also stimulates the digestive system to absorb more calcium ions, used to make bones strong.
How is the resting metabolic rate measured?
Measured with the body at rest, in a warm room longer after the person has had their last meal.
What hormone affects metabolic rate?
Thyroxin, released by the thyroid gland.
What does the hormone thyroxine do?
- it is taken into and affects many different types of cells.
- it causes heart cells to contract more quickly and strongly.
- increases rate at which proteins and carbohydrates are broken down inside cells.
Define the term negative feedback.
A control mechanism that reacts to a change in condition, such as temperature, by trying to bring the condition back to a normal level.
Give an example of endocrine gland which is a target organ for another hormone:
The sex hormone oestrogen and testosterone are released in the reproductive system, they stimulate the release of growth hormones. The release of sex hormones increases during puberty and this why there is an increase in growth rate at this time.
What is the amount of they rosins produced controlled by?
Hormones released by 2 other glands:
- hypothalamus (which releases TRH)
- pituitary (which releases TSH)
The levels of each of these hormones stimulates the amount of other hormones in this chain being produced. It is also an ex plane of negative feed back.
In what situations are a lot of adrenalin released and how?
Normal levels of adrenalin are quite low. However, in a frightening or exciting situation an increase in impulses from neurones reaching the adrenal glands from the spinal chord triggers the release of large amounts of adrenalin in the blood.
What is one of the target organs of adrenalin and what does it do at this target organ?
The liver is one of the target organs of adrenalin. Here it causes the breakdown of storage substances called glycogen. Glycogen is a polymer made from glucose molecules. When glycogen is broken down glucose molecules can be released into the blood providing additional glucose for respiration. (This gives energy for ‘fight or flight’)
What is glucagon?
A polymer made of glucose molecules.
What are the target organs of adrenalin?
- liver
- heart
- blood vessels
How does adrenalin affect the heart?
Heart muscle cells contract:
- more rapidly, which increases the heart rate.
- more strongly, which increases blood pressure.
How does adrenalin affect blood vessels?
It has 2 affects depending on the type of blood vessel:
- diameter blood vessels leading to muscles widens, which increases blood flow to muscles.
- diameter of blood vessels leading to other organs narrows, which reduced blood flow to those organs and increases blood pressure.
How does adrenalin affect the liver?
Liver cells turn glycogen into glucose and release into the blood which increases blood sugar concentration.
What is the menstrual cycle?
A cycle of changes in a women’s reproductive system and takes about 28 days. The cycle continues from puberty (around 12 years old) to menopause (around 50 years old) and prepares a woman’s body for the fertilisation if an egg cell, leading to pregnancy.
What is menstruation?
This occurs in day 1 of the menstruated cycle. It is the break down and loss of lining of the uterus along Sotheby’s the unfertilised egg. This causes a period.
What is ovulation and when does it occur?
Ovulation occurs when the ovaries release an egg?
What happens in days 1-5 of the menstrual cycle?
Menstruation happens during this time. The uterus lining breaks down and is lost with unfertilised egg.
What happens during days 6-12 of the menstrual cycle?
When menstruation ends the uterus lining starts to thicken again.
What happens during days 13-15 of the menstrual cycle?
Ovulation- when the ovaries release an egg cell.
What happens during days 16-28 of the menstrual cycle?
Fertilisation leading to pregnancy is most likely at this stage. The uterus lining continues to thicken. The egg cell travels along the oviduct to the uterus. The cycle then starts again.
What is the menstrual cycle controlled by?
The cycle is controlled by the sex hormones oestrogen and progesterone.
What is contraception?
The prevention of fertilisation.
Give 3 types of contraception methods, how they work and how effective they are:
Condom: placed over penis and prevents sperm enter in vagina. It has a 98% success rate in preventing fertilisation.
Diaphragm/cap: placed over the cervix (entrance to the uterus) prevents speed in the vagina entering the uterus. It has a 92%-96% success rate in preventing fertilisation.
Hormone pill or implant placed under skin: release hormones to prevent ovulation and thicken mucus at the cervix, making it difficult for sperm cells to pass through.
What controls the release of the hormones FSH and LH from the pituitary gland?
The release of these hormones is controlled by the concentration of oestrogen (which increases as the egg follicle matures) and progesterone (which is released after ovulation when the egg follicle becomes a structure called the corpus luteum).
What is Assisted Reproductive Technology (ART)?
This uses hormones and other techniques to increase the chance if pregnancy. It is used to help some couples who struggle to have a child become pregnant.
What is Clomifene therapy and how is it used?
This is useful for women who rarely or never release and egg cell during the menstrual cycles. Clomifene is a drug that helps to increase the concentration of FSH AND LH in the blood.
What is IVF?
In Vitro Fertilisation. This is another ART technique. This can overcome problems such as blocked oviducts in the woman, or of the man produced very few healthy sperm cells. Any healthy embryos not used in the first attempt at pregnancy may be frozen and stored for use of another time.